Step-by-step design of poly (ε-caprolactone) /chitosan/Melilotus officinalis extract electrospun nanofibers for wound dressing applications.

Composition of polymers and choosing the type of solvents in electrospinning systems is of great importance to achieve a mat with optimal properties. In this work, with emphasizing the influence of a novel solvent system, an electrospun wound dressing was designed in four steps. Firstly, to study the effect of polymer-solvent interactions and electrospinning distance, a constant amount of polycaprolactone (PCL) was dissolved at different compositions of formic acid (FA)/dichloromethane (DCM) and was electrospun at different distances. The composition of 80FA/20DCM and distance of 15 cm were selected as optimal conditions by lowest average diameter of fibers and simultaneously good surface uniformity. In the second step, the concentration of PCL was considered variable to achieve the lowest diameter of fibers. Finally, in the third and fourth steps, different concentrations of chitosan (CN) and constant dosage of Melilotus officinalis (MO) extract were added to the solution. The extract contained fibers had a mean diameter of 275 ± 41 nm which is in the required condition for wound caring. Eventually, the optimized PCL/CN and PCL/CN/MO specimens were evaluated by FTIR, DSC, Tensile, water contact angle, antibacterial assays, cell viability, and drug release analysis for determining their function and properties.